Abstract: Objective To study the effect of ultraviolet B (UVB) irradiation on the transcriptional activity of nuclear factor KB(NF-κB) in human epidermal keratinocytes.Methods Normal human epidermal keratinocytes were isolated from healthy children foreskin and cultured at 37℃ in 5% CO₂.Cultured keratinocytes were irradiated with UVB at the dose of 20,60 and 120 mJ/cm²,respectively.The whole cell, nuclear and cytoplasmic protein of keratinocytes was extracted at 0,2,24,and 48 hours after the irradiation. The whole cell and nuclear NF-κB/p65 protein as well as cytoplasmic NF-κB Inhibitor(IκB-a) protein were detected by Western blotting.The transcriptional activity of NF-κB was analyzed by electrophoretic mobility shift assay (EMSA).Results UVB irradiation significantly increased (P<0.05) the protein expression of NF-κB in both the whole cell and the nucleus of keratinocytes in a dose-dependent manner;the increase began at 2 h,peaked at 24 h,and maintained with high expression until 48 h after the irradiation. The transcriptional activity of NF-κB was improved at different time points after UVB irradiation of different doses,while the expression of Iκd3-a was significantly decreased (P<0.05) by the irradiation.Conclusion UVB irradiation can improve the transcriptional activity of keratinocytes,likely by the degradation of IκB-a.

Key words: UVB, Keratinocytes, NF-kappa B